The fontanelle tonometer: a noninvasive method for measurement of intracranial pressure.

The use of a modified pneumotonometer as a noninvasive method to measure intracranial pressure through the fontanel was evaluated in the animal laboratory and in the clinical setting. Pressure measured with the tonometer from a surgically created fontanel in an adult mongrel dog demonstrated good correlation with pressure measured from an epidural balloon catheter. Pressure recorded with the tonometer was compared with direct measurements in a single infant. There were 20 paired measurements with a correlation coefficient of 0.91. Fontanel pressure was measured in 72 healthy infants. The mean pressure was 7.0 mm Hg with a standard deviation of 1.75. This result compares favorably with previous reports utilizing other methods. The machine is safe and simple to use.

Noninvasive diagnosis of neonatal asphyxia and intraventricular hemorrhage by Doppler ultrasound.

The cerebrovascular hemodynamic alterations in asphyxia and intracerebral-intraventricular hemorrhage were determined by monitoring the pulsatile flow changes in the anterior cerebral arteries using Doppler ultrasound. The pulsatility index measurements, which were calculated from the recorded changes in Doppler frequency shifts, were obtained in four groups of newborn infants with the following diagnoses: Group I--normal term (n=21); Group II--asphyxia (n=12); Group III--IC-IVH (n=14); and Group IV--asymptomatic preterm (n=11). There was no significant difference between PI values of Groups I and IV. Compared to normal term infants, those diagnosed as having asphyxia had significantly lower PI measurements and those with IC-IVH had significantly higher PI values than the asymptomatic pretern infants. Serial Doppler studies were also performed in 22 preterm infants with respiratory distress. One-half of these infants subsequently developed IC-IVH. Prior to hemorrhage, their PI measurements were significantly lower than those who did not eventually have the complication. The low PI values in asphyxia and prior to the onset of IC-IVH indicate vasodilation and decreased resistance to blood flow. In IC-IVH, the high PI measurements denote the opposite. In infants with respiratory distress in the presence of significant vasodilation and lowered vascular resistance, CBF may increase to excessive levels, resulting in IC-IVH.